BoilerFaultCodesYour boiler's main control board is receiving an incorrect electrical signal from the flame sensor, meaning the system cannot safely confirm if the burner is lit.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flame monitor input signal is outside the limits (0 or 5 V): electronics defective
What causes this fault?
This fault occurs when the boiler's central brain receives a conflicting electrical signal regarding the presence of a flame, causing it to shut down for safety. The most common reason is an internal electronic failure within the main control board or a short circuit in the wiring connecting the sensors. Essentially, the boiler can no longer trust its own sensors to tell if it is burning gas safely.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like F.67 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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